Balance trainer, mold assembly for making the same, and manufacturing process thereof

ABSTRACT

A balance trainer having a dome and a base formed integrally is provided. Also, a mold assembly for manufacturing the balance trainer that has a dome mold, a girdle, and a cover is provided. The girdle is sleeved on the dome mold and the cover is fixed on the girdle and thereby a cavity is formed in the mold assembly. Furthermore, a manufacturing process of the balance trainer is also provided. The process has the following steps: preparing ingredients of the dome and the base; feeding the ingredients of the dome into the dome mold; fixing a membrane on the dome mold via the girdle; feeding the ingredients of the base; sealing the ingredients via the cover; and then rotational molding. With the process and the mold, the rotational molding step can mold two materials at the same time, so the product can have two parts with different hardness.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to fitness equipment and a manufacturingmold and process form making the fitness equipment, especially to abalance trainer and a manufacturing mold and process form making thebalance trainer.

2. Description of the Prior Arts

A balance trainer, or both-sides-up ball (a.k.a. bosu ball) is shapedlike a semi-ball and comprises two portions: a dome portion being anupper side of the balance trainer and a plane portion being a bottomside of the balance trainer. Both of the two sides of the balancetrainer can be used for training. With the balance trainer, a sense ofbalance and strengths of core muscles may be improved.

In the conventional balance trainers, the dome portion and the planeportion are connected via a connecting means. In other words, the domeportion and the plane portion are made separately and then fixedtogether. Therefore, the joint portions of the conventional balancetrainers are fragile and easy to be broken.

To overcome the shortcomings, the present invention provides a balancetrainer, a mold assembly for making the balance trainer, and amanufacturing process for making the balance trainer via said moldassembly to mitigate or obviate the aforementioned problems.

SUMMARY OF THE INVENTION

The main objective of the present invention is to provide a balancetrainer, and a mold assembly and a manufacturing process of making thebalance train that is formed integrally.

The balance trainer comprises a dome and a base. The dome has an outeredge. The base is formed with the dome integrally and has a connectingedge. The connecting edge is melt-connected to the outer edge of thedome.

The mold assembly comprises a dome mold, a girdle, and a cover. The domemold has a domed cavity therein. The girdle is sleeved and fixed on thedome mold and encompasses the domed cavity. A surface of the domedcavity and an inner surface of the girdle form a continuous curvedsurface together. The cover is fixed on the girdle and encloses thecontinuous curved surface. The girdle is located between the dome moldand the cover.

The manufacturing process includes the following steps in sequence: (1)preparing ingredients for making a dome and ingredients for making abase respectively; (2) feeding the ingredients for making the dome intoa dome cavity of a dome mold of a mold assembly; (3) fixing a membraneon the dome mold and thereby the ingredients of making the dome enclosedby the membrane and the dome mold; and then mounting the girdle on themembrane, a diameter of the membrane being larger than an outer diameterof a girdle of the mold assembly; (4) feeding the ingredients for makinga base on the membrane and in the girdle; (5) covering and sealing thegirdle and dome mold via a cover of the mold assembly, and thereby theingredients for making a base enclosed by the membrane, the girdle, andthe cover; (6) rotational molding, which includes the following acts insequence: putting the mold assembly into a rotary furnace and rollingand heating the mold assembly; (7) finishing, which includes thefollowing acts in sequence: taking out the mold assembly from the rotaryfurnace, cooling the mold assembly, and taking out the dome and the basefrom the mold assembly.

The balance trainer has the dome and the base formed integrally, whichis different from the conventional balance trainer that is made viafixing a dome and a base manufactured separately by a third connectingcomponent. In the balance trainer of the present invention, the dome andthe base are melt-connected during molding the dome and molding the baseat the same time. Therefore, an integral piece is formed with twodifferent degrees of hardness.

One of the advantages of the balance trainer of the present invention isthat the dome and the base are prevented from detaching from each other,and thereby the strength of the balance trainer of the present inventionis higher than that of the conventional balance trainer. For example,the balance trainer of the present invention can sustain burden over2000 kg. Besides, the base has structures for selectively mountingresistance bands without other components for fixing. Therefore, themanufacturing process is simplified. After the balance trainer ismounted with a resistance band, the user can balance on the balancetrainer via pulling the resistance band.

In conventional rotational molding, one cavity of a mold only can be fedwith ingredients under one formula, so the product only have onehardness and one color. However, the manufacturing process of thepresent invention can make a product with a soft part (i.e. the dome)and a hard part (i.e. the base) so the manufacturing process of thepresent invention overcomes the defect of conventional rotationalmolding. Therefore, the product may be formed integrally and beautiful,weight of the product may be reduced, and manufacturing cost is lowerthan that of the conventional manufacturing process.

Other objectives, advantages and novel features of the invention willbecome more apparent from the following detailed description when takenin conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a balance trainer in accordance with thepresent invention shown with resistance bands;

FIG. 2 is a bottom view of the balance trainer in FIG. 1;

FIG. 3 is a sectional view of the balance trainer in FIG. 1;

FIG. 4 is a side view of a mold assembly in accordance with the presentinvention for manufacturing the balance trainer in FIG. 1;

FIG. 5 is an exploded view of the mold assembly in FIG. 4;

FIG. 6 is a sectional view of the mold assembly in FIG. 4;

FIG. 7 is a perspective view of a girdle of the mold assembly in FIG. 4;

FIG. 8 is an enlarged sectional view of the mold assembly in FIG. 4;

FIG. 9 is a flow chart in accordance with the present invention formanufacturing the balance trainer in FIG. 1 and via the mold assembly inFIG. 4;

FIG. 10 is a detailed flow chart of the step “Feeding ingredients into amold assembly” in FIG. 9; and

FIG. 11 is an enlarged view of the buckle in FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to FIGS. 1 to 3, a balance trainer made integrally viarotational molding in accordance with the present invention is provided.The balance trainer comprises a dome 1 and a base 2. The dome 1 isflexible and resilient and hardness thereof is lower than SG4. Hardnessof the base 2 is higher than SG5 and thereby the base 2 is strong enoughto support the dome. In this embodiment, the dome 1 is made from softPVC and the base 2 is made from hard PVC. In this embodiment, thebalance trainer is hollow, but it is not limited thereto, as the balancetrainer may contain stuffing material or may be solid. Normally, thedome 1 is arranged to face upward and, correspondingly, the base 2 facesdownward. Therefore, the up-down relation in the balance trainer isdefined accordingly.

The base 2 comprises a connecting ring 21 and a bottom plate 22. A lowerend surface of the dome 1 fits with an upper end surface of theconnecting ring 21. In other words, a dimension of the lower end surfaceof the dome 1 is equal to a dimension of the connecting ring 21 of thebase 2. The lower end surface of the dome 1 is melt-connected to theupper end surface of the connecting ring 21, and thus the dome 1 and thebase 2 are formed integrally.

Ingredients of the dome 1 include Polyvinyl chloride paste resin, aplasticizer, a viscosity reducer, and a stabilizing agent. An amount ofthe Polyvinyl chloride paste resin ranges from 90 parts to 100 parts byweight; an amount of the plasticizer ranges from 45 parts to 55 parts byweight; an amount of the viscosity reducer ranges from 3.5 parts to 4.5parts by weight; and an amount of the stabilizing agent ranges from 1part to 3 parts by weight.

The Polyvinyl chloride paste resin of the dome 1 may be TPH-31 Polyvinylchloride paste resin or PB-1302 Polyvinyl chloride paste resin, but itis not limited thereto.

The plasticizer of the dome 1 may contain epoxidized soybean oil (ESBO),tributyl citrate (TBC), dioctyl terephthalate (bis(2-ethylhexyl)benzene-1, 4-dicarboxylate or Di (2-ethylhexyl) terephthalate,abbreviated DOTP), or combinations thereof.

The viscosity reducer of the dome 1 may contain PVC viscosity reducerD-80, 2,2,4-trimethylpentane-1,3-diyl bis (2-methylpropanoate) (TXIB),or a combination thereof.

The stabilizing agent of the dome 1 may be liquid calcium zincstabilizer.

In this embodiment, the ingredients of the dome 1 may include, byweight, 93.9 parts of Polyvinyl chloride paste resin, 50.45 parts ofplasticizer (which may include 38.5 parts of TBC, 6.85 parts of DOTP,5.1 parts of ESBO), 4.05 parts of PVC viscosity reducer D-80, and 1.65parts of liquid calcium zinc stabilizer.

Ingredients of the base 2 include Polyvinyl chloride paste resin, aplasticizer, a viscosity reducer, and a stabilizing agent. An amount ofthe Polyvinyl chloride paste resin ranges from 180 parts to 220 parts byweight; an amount of the plasticizer ranges from 35 parts to 45 parts byweight; an amount of the viscosity reduction ranges from 14 parts to 18parts by weight; and an amount of the stabilizing agent ranges from 1part to 3 parts by weight. The plasticizer of the base 2 may containESBO, TBC, acetyl tributyl citrate (ATBC), DOTP, 1,2-Cyclohexanedicarboxylic acid diisononyl ester (DNICH), or combinations thereof.

The viscosity reducer of the base 2 may contain PVC viscosity reducerD-80, TXIB, or a combination thereof.

The stabilizing agent of the base 2 may be liquid calcium zincstabilizer.

In this embodiment, the ingredients of the base 2 may include, byweight, 192 parts of the Polyvinyl chloride paste resin, 40 parts of theplasticizer (which may include 32 parts of TBC and 8 parts of ESBO),12.75 parts of the viscosity reducer (which may include 10.75 parts ofPVC viscosity reducer D-80 and 5.25 parts of TXIB), and 2 parts ofliquid calcium zinc stabilizer.

The dome 1 comprises a non-slip pattern 11. The non-slip pattern 11 maybe a plurality of protrusions mounted on an outer surface of the dome 1.In this embodiment, the protrusions may be a plurality of ribs. However,the non-slip pattern 11 may be a plurality of dimples or grooves. Withprotrusions or dimples of the non-slip pattern 11 densely arranged onthe outer surface of the dome 1, the dome 1 is non-slip and provides amassaging effect.

The ingredients of the connecting ring 21 and the bottom plate 22 may bethe same. The connecting ring 21 is mounted on the bottom plate 22.Therefore, the connecting ring 21 is located between the dome 1 and thebottom plate 22. The connecting ring 21 is a closed ring or loop. Anouter diameter of the upper end surface of the connecting ring 21 isequal to that of the lower end surface of the dome 1.

A lower end surface of the connecting ring 21 is mounted on the bottomplate 22. An outer diameter of the bottom plate 22 is larger than thatof the lower end surface of the connecting ring 21. Therefore, a portionof the bottom plate 22 that extends out of the connecting ring 21 isdefined as a protrusion 23. Please also refer to FIG. 11. The base 2comprises at least one buckle 24, a plurality of paving pads 25, and anon-slip pattern 26 on a lower surface of the bottom plate 22.

In this embodiment, an amount of the buckle 24 is two. The two buckles24 are formed on a periphery of the base 2; in other words, the buckles24 is formed integrally on the protrusion 23 of the base 2. Precisely,the buckles 24 are located on two ends of a diameter of the protrusion23. Each one of the buckles 24 comprises a notch 241 and a through hole242. The notch 241 is concaved from an outer edge of the protrusion 23.The through hole 242 is formed through the protrusion 23 and is innerthan the notch 241. In another embodiment, the amount of the buckle 24may be four or any other amount.

The paving pads 25 are configured to support the base 2 and prevent thebase 2 from sliding. The paving pads 25 are arranged on the lowersurface of the bottom plate 22 in a peripheral direction and spaced fromeach other by the same distance. A shape of each paving pad 25 may be acylinder as shown in FIG. 3, but it is not limited thereto. For example,each paving pad 25 may be shaped like a crescent.

The non-slip pattern 26 covers a portion, where a user stands on, of thelower surface of the bottom plate 22 as shown in FIG. 1. The non-slippattern 26 may be shaped like a human foot, but it is not limitedthereto.

With reference to FIGS. 4 to 6, a mold assembly for manufacturing abalance trainer in accordance with the present invention is provided.The mold assembly comprises a dome mold 3, a girdle 4, and a cover 5.The girdle 4 is mounted between the dome mold 3 and the cover 5.

In this embodiment, the dome mold 3 is a bottom part of the moldassembly, the cover 5 is a top part of the mold assembly, and the girdle4 is a middle part of the mold assembly. Therefore, the up-down relationin the mold assembly is defined accordingly. However, the relation ofthe dome mold 3, the girdle 4, and the cover 5 are not limited thereto,as they may be arranged inversely or horizontally. Besides, a firstdirection points downward and a second direction points upward.

During forming a balance trainer via the mold assembly of the presentinvention, the balance trainer is upside down. In other words, as thebalance trainer is contained in the mold assembly, the dome 1 of thebalance trainer is lower than the base 2 of the balance trainer; it isnot limited thereto.

The dome mold 3 comprises a supporter 30 and a main body 31. The mainbody 31 is supported by the supporter 31. Besides, the assembled moldassembly is supported by the supporter 31, too.

The dome mold 3 has a domed cavity 32 inside the main body 31.Therefore, the domed cavity 32 has an opening facing upward and thedomed cavity 32 is dome-shaped. In this embodiment, the domed cavity 32has a plurality of non-slip grooves 33 on a surface of the domed cavity32. A shape of each non-slip groove 33 is made according to the shape ofthe non-slip pattern 11 of the balance trainer. In other words, concaveor convex parts of the non-slip grooves 33 are opposite the non-slippattern 11 of the balance trainer. Therefore, in this embodiment, eachnon-slip groove 33 extends downward and has an opening facing upward.

The main body 31 forms a mounting stage 34 for connecting, fixing andpositioning the mounted girdle 4. The mounting stage 34 is formed via anannular protrusion protruding from a peripheral surface of the main body31 and near a top surface of the main body 31 so that the girdle 4 canbe put on the annular protrusion and sleeve the annular protrusion.

Please refer to FIGS. 5, 7 and 8. The girdle 4 comprises an inner ring41 and an outer ring 42. The inner ring 41 and the outer ring 42 areconcentric. An outer surface of the inner ring 41 fits to and abuts aninner surface of the outer ring 42.

The inner ring 41 has a first end surface facing toward the firstdirection and a second surface facing toward the second direction, i.e.,the first end surface faces the dome mold 3 and the second end surfacefaces the cover 5. Similarly, the outer ring 42 has a first end surfacefacing in the first direction and a second surface facing in the seconddirection, i.e., the first end surface faces the dome mold 3 and thesecond end surface faces the cover 5. Therefore, the first end surfacesof the inner ring 41 and the outer ring 42 are named as lower surfaces411 and 421 respectively and the second end surfaces of the inner ring41 and the outer ring 42 are named as upper surfaces 412 and 422respectively.

The lower surface 411 of the inner ring 41 is higher than the lowersurface 421 of the outer ring 42. The lower surface 411 of the innerring 41, the lower surface 421 of the outer ring 42, and a first annularsurface 423, which is between said two lower surfaces 411 and 421, ofthe outer ring 42 form an annular joined portion 43 together. Theannular joined portion 43 is sleeved on the mounting stage 34 of themain body 31. In other words, the annular joined portion 43 receives anupper portion of the annular protrusion of the main body 31, and therebythe surface of the domed cavity 32 and the inner surface of the innerring 41 connect to each other and form a continuous surface together asshown in FIG. 8. In this embodiment, the domed cavity 32 and the innerring 41 form a cavity together.

The upper surface 412 of the inner ring 41 is lower than the uppersurface 422 of the outer ring 42. The upper surface 412 of the innerring 41, the upper surface 422 of the outer ring 42, and a secondannular surface 424, which is between said two upper surfaces 412 and422, of the outer ring 42 form a stepped stage 44. The stepped stage 44is configured to join the cover 5. A thickness of the bottom plate 22 ofthe manufactured balance trainer is decided by a distance between saidtwo lower surfaces.

Please refer to FIGS. 5 and 8. The cover 5 comprises a main body shapedlike a round plate, and a rim 53. The main body of the cover 5 is around plate. The rim 53 is mounted on a periphery of the main body ofthe cover 5. The rim 53 is detachably sleeved on the joined stage 45 ofthe girdle 4. Therefore, an inner diameter of the rim 53 is equal to anouter diameter of the joined stage 45.

The cover 5 further has a plurality of pad cavities 51 and a pluralityof non-slip grooves 52 on the main body of the cover 5. The pad cavities51 are arranged in a peripheral direction on the main body of the cover5. An opening of each pad cavity 51 faces the domed cavity 32. Anopening of each non-slip groove 52 faces the domed cavity 32, too.

The mold assembly of the present invention is assembled via thefollowing steps: the girdle 4 is mounted on a top portion of the domemold 3, the cover 5 is mounted on a top portion of the girdle 4, andthereby a closed chamber is formed therein. The domed cavity 32 of thedome mold 3 is configured to mold the dome 1 of the balance trainer, andthe girdle 4 and the cover 5 are configured to mold the base 2 of thebalance trainer. Before molding, a membrane 12 is mounted between thedome mold 3 and the girdle 4.

The girdle 4 comprises at least one bump on the stepped stage 44. Inthis embodiment, an amount of the bump is two, but and the two bumps aremounted on the stepped stage 44 in symmetry. However, the amount and theposition of the bumps are not limited thereto. After rotational molding,two notches 241 are formed on the bottom plate 22. The notches 241 areconfigured to mount buckles 24 for selectively mounting a resistanceband 7 (as shown in FIG. 1). In this embodiment, the buckles 24 areformed on the bottom plate 22 integrally.

Then please refer to FIG. 9. A manufacturing process of a balancetrainer formed integrally in accordance with the present invention isprovided. The manufacturing process includes the following steps insequence:

1. Preparation:

According to the hardness of the dome 1 and the base 2 of the balancetrainer, preparing and blending ingredients for making a dome andingredients for making a base respectively. The recipes of making thedome 1 and the base 2 via rotational molding are shown as follows:

Dome Base Material Weight Material Weight Polyvinyl chloride paste  939g Polyvinyl chloride 1920 g  resin paste resin TBC as plasticizer 385.5g  TBC as plasticizer 320 g DOTP as plasticizer 68.5 g ESBO asplasticizer  80 g ESBO as plasticizer   51 g D-80 as viscosity 107.5 g  reduction D-80 as viscosity 40.5 g TXIB as viscosity 52.5 g  reductionreduction Liquid calcium zinc 16.5 g Liquid calcium zinc  20 gstabilizing agent stabilizing agent

following acts in sequence: weighting ingredients according to the tableabove, putting said ingredients into a container, blending saidingredients for 1 hour, disposing said ingredients at a vacuumed statefor 4 hours, adding color paste or pigment into said ingredientsaccording to a desired color of the dome 1 (for example, adding whitepaste 7.5 g and colored paste 0.25), blending said ingredients again for1 hour, and disposing said ingredients at a vacuumed state for 0.5 hour,thereby completing the preparation.

The step for preparing the ingredients of the base 2 includes thefollowing acts in sequence: weighing ingredients according to the tableabove, putting said ingredients into a container, blending saidingredients for 1 hour, disposing said ingredients at a vacuumed statefor 4 hours, adding color paste or pigment into said ingredientsaccording to a desired color of the dome 1 (for example, adding whitepaste 3.75 g and colored paste 0.08), blending said ingredients againfor 1 hour, and disposing said ingredients at a vacuumed state for 0.5hour, thereby completing the preparation.

2. Feeding:

The step for feeding the ingredients for making the dome 1 into the moldassembly includes the following acts in sequence: feeding saidingredients for making the dome 1 into the dome mold 3; shearing a PVCmembrane 12 so that a diameter of the PVC membrane 12 is larger than anouter diameter of the girdle 4, putting the PVC membrane 12 on a top ofthe dome mold 3 and covering an opening of the dome mold 3 via the PVCmembrane 12, sleeving and fixing the girdle 4 on the top of dome mold 3,evening the PVC membrane 12, fixing the PVC membrane 12; feeding theingredients for making the base 2 on the PVC membrane 12 and within thegirdle 4, and then covering and sealing the ingredients of the base 2via the cover 5, thereby completing the feeding step.

In this embodiment, ingredients of the PVC membrane 12 may be the sameas those of the dome 1, but it is not limited thereto. Besides, the timeof shearing of the membrane 12 may be earlier; for example, the shearingcan be done even before the manufacturing process of the presentinvention or after covering via the cover 5.

3. Rotational Molding:

Fixing the mold assembly in a rotary furnace; heating the mold assemblyand keeping the temperature at 332° C., rolling the mold assembly at1100 rpm for 14 minutes, but it is not limited thereto, as the rollingrate and temperature may be different according to differentingredients.

4. Cooling:

Taking out the mold assembly, immersing the mold assembly into a waterpool for 25 seconds twice. After 5.5 minutes, open the mold assembly andtake out the shaped dome 1 and base 2. Each water pool is maintainedbelow 50° C.

In this embodiment, before rotational molding, the ingredients formaking the dome 1 and the base 2 are separated by the membrane 12. Afterrotational molding, the lower end surface of the dome 1 and the upperend surface of the base 2 are melt-connected to the membrane 12 andthereby forming a balance trainer integrally.

Because the membrane 12 is mounted between the dome mold 3 and thegirdle 4, the dome 1 formed between the dome mold 3 and the membrane 12is made from soft PVC, and the base 2 formed amid the membrane 12, thegirdle 4, and the cover 5 is made from hard PVC. After demolding, theconnecting ring 21 of the balance trainer corresponds to the inner ring41 of the girdle 4 and the bottom plate 22 of the balance trainercorresponds to the portion higher than the inner ring 21.

5. Assembling Accessories, Inspecting, and Packaging.

Even though numerous characteristics and advantages of the presentinvention have been set forth in the foregoing description, togetherwith details of the structure and features of the invention, thedisclosure is illustrative only. Changes may be made in the details,especially in matters of shape, size, and arrangement of parts withinthe principles of the invention to the full extent indicated by thebroad general meaning of the terms in which the appended claims areexpressed.

What is claimed is:
 1. A balance trainer comprising: a dome forming: anouter edge; and a base formed with the dome integrally and located underthe dome, the base comprising: a bottom plate; and a connecting ringformed integrally on the bottom plate and extending upward from thebottom plate, the connecting ring forming a connecting edge facingupward and melt-connected to the outer edge of the dome.
 2. The balancetrainer as claimed in claim 1, wherein an outer diameter of the outeredge of the dome and an outer diameter of the connecting edge of thebase are equal in size.
 3. The balance trainer as claimed in claim 1further comprising: at least one non-slip pattern on an outer surface ofthe dome.
 4. The balance trainer as claimed in claim 1 furthercomprising: at least one buckle formed integrally on a protrusion of thebase; each one of the at least one buckle comprising: a notch concavedfrom an outer edge of the protrusion; and a through hole formed throughthe protrusion and inner than the notch.
 5. The balance trainer asclaimed in claim 1 further comprising: a plurality of paving padsmounted on the base.
 6. The balance trainer as claimed in claim 1,wherein: ingredients of the dome include: polyvinyl chloride pasteresin, an amount thereof ranging from 90 parts to 100 parts by weight; aplasticizer, an amount thereof ranging from 45 parts to 55 parts byweight; a viscosity reducer, an amount thereof ranging from 3.5 parts to4.5 parts by weight; and a stabilizing agent, an amount thereof rangingfrom 1 part to 3 parts by weight; and ingredients of the base include:polyvinyl chloride paste resin, an amount thereof ranging from 180 partsto 220 parts by weight; a plasticizer, an amount thereof ranging from 35parts to 45 parts by weight; a viscosity reducer, an amount thereofranging from 14 parts to 18 parts by weight; and a stabilizing agent, anamount thereof ranging from 1 part to 3 parts by weight.
 7. The balancetrainer as claimed in claim 6, wherein, in the dome: the plasticizercontains: epoxidized soybean oil, tributyl citrate, dioctylterephthalate, or combinations thereof; the viscosity reducer contains:PVC viscosity reducer D-80, 2,2,4-trimethylpentane-1,3-diylbis(2-methylpropanoate), or a combination thereof; and the stabilizingagent contains liquid calcium zinc stabilizing agent.
 8. The balancetrainer as claimed in claim 6, wherein, in the base: the plasticizercontains: epoxidized soybean oil, tributyl citrate, acetyl tributylcitrate, dioctyl terephthalate, DNCH, or combinations thereof; theviscosity reducer contains: PVC viscosity reducer D-80,2,2,4-trimethylpentane-1,3-diyl bis(2-methylpropanoate), or acombination thereof; and the stabilizing agent contains liquid calciumzinc stabilizing agent.